A switch of the above-mentioned type can generally constitute a circuit breaker, which handles disconnection currents of more than 10 kA in a voltage range above 70 kV. A switch such as this has a switch housing which is filled with an insulating gas, which has arc quenching characteristics, for example, based on sulfur hexafluoride, nitrogen and/or carbon dioxide, generally at a pressure of up to several bar. In order to achieve rapid dielectric strength recovery of a breaker gap, which is formed between two opening contact members during disconnection of a current, the contact members are driven in opposite directions to one another. The force required to do this is applied by a single drive in the switch. A direction-changing transmission is therefore fitted to an insulating nozzle in the switch. The insulating nozzle is attached to a first one of the two contact members. This transmission transmits force, which has been introduced into the first contact member from the drive, to the second contact member, or else, vice versa, transmits force, which has been introduced into the second contact member from the drive, to the first contact member. The force which occurs in this case is considerable. The attachment of the nozzle to the first contact member is relatively simple, since the contact member has a centrally positioned arcing contact and a hollow rated current contact which coaxially surrounds the arcing contact and in which the first of the two ends of the nozzle can be fastened in a dielectrically safe manner. Since the nozzle is arranged such that the nozzle can move with respect to the second contact member, the coupling of the direction-changing transmission to the second end of the nozzle, which is used for blowing out quenching gas, is relatively complex, not least because gas-tightness and the control of the electrical field in the area of the coupling point must also be taken into account here.
A switch of the type mentioned initially is described in EP 0 809 268 A2 and U.S. Pat. No. 6,271,494 B1. In this switch, the force of the switch drive is introduced into a first contact member, to which an insulating nozzle is fitted, and is transmitted via a direction-changing transmission to the second contact member, which is driven in the opposite direction to the first contact member. As described in EP 0 809 268 A2, the insulating nozzle has an external bead, which is arranged at the blowing-out end of the nozzle and behind which a first clamping ring is latched in. A second clamping ring is arranged in front of the bead and supports the first clamping ring and/or the end of the nozzle, to prevent the first clamping ring from being unlocked. A drive element for the direction-changing transmission can be coupled to at least one of the two clamping rings. In order to allow the first clamping ring to latch in, the first claiming ring or the end of the nozzle must be elastically deformable. However, in general, this requires slots in the nozzle end or in the first clamping ring, which are positioned along the switch axis and adversely affect the gas-tightness and the dielectric strength. Additional means are therefore required, such as a field electrode to control the electrical field in the area of the coupling.
In a switch of the type mentioned initially, which is described in EP 1 983 538 A1, the force of the switch drive is introduced into the second contact member and is transmitted via a direction-changing transmission and an insulating nozzle to the first contact member, to which the nozzle is fitted and which is driven in the opposite direction to the second contact member. An annular body is arranged at the blowing-out end of the insulating nozzle, which is fitted with a drive element of the direction-changing transmission, and is attached to an external bead on the nozzle with the aid of a screw connection.